Internet Protocol (IP) multicast refers to the sending of packets to a group of receivers. An IP multicast group address is established, and senders and receivers use the group address to send and receive an IP multicast stream of packets. A source uses the group address as the IP destination address in the packets. Receivers use the group address to inform the network that they want to receive packets sent to that group address. The protocol typically used by receivers to join a group is referred to as the Internet Group Management Protocol (IGMP).
IP multicasting may be used to deliver Internet Protocol Television (IPTV) content. IPTV is a service through which television and other video content is delivered to an end user over a packet-switched network, such as the Internet. An IPTV subscriber receives a set-top box (STB) from the IPTV provider, which is also typically the internet service provider for the subscriber. The STB is able to access the IPTV service over the internet through other equipment at the customer premises, such as a modem, an Optical Network Termination (ONT), a residential gateway, etc. This equipment connects the STB to an access network that provides connectivity to the internet. For example, the access network may comprise a Digital Subscriber Line (xDSL) network, a Passive Optical Network (PON), a cable network, etc. When connected to the Internet, IPTV servers provide video stream(s) to the STB for viewing over the subscriber's television or other suitable display. The IPTV subscriber can view an Electronic Programming Guide (EPG) displayed by the STB, and select programs or videos to watch.
IP multicast delivery is advantageous because it provides efficient bandwidth usage over the Internet and/or over the access network. For example, a sender transmits packets of an IP multicast stream to a group address where the packets include content desired by the receiver, such as IPTV content. Nodes in the network (e.g., switches, routers, etc.) replicate the packets of the IP multicast stream so that the packets reach each receiver in the group. The sender only has to send the packets of the IP multicast stream once, and the network infrastructure replicates the IP multicast stream for delivery to the receivers. Internet service providers may reserve bandwidth for IPTV services or other IP multicast delivery services so that a quality of delivery may be guaranteed. Despite the guaranteed quality of delivery for IP multicast delivery, nodes and/or links in the network may become defective which interrupts transmission of an IP multicast stream. Therefore, a subscriber may not be able to view the content. For IPTV service in particular, troubleshooting is a main contributor to the high operational cost of the IPTV service. Therefore, service providers continue to look for ways to quickly and easily detect a node or link at fault, and report the fault to a management system.